Chapter - 5 :- separation of substances

Table of Contents

EXERCISE

Section - A

A. Oral Questions :-

1. How do the properties of a substance help you to determine the method to be used for separation of components of mixture?

Ans :-  separation of components from mixture is done on the basis of their properties. following is the method of separation of component on the basis of properties :- 

  • Separation of solid substances from a mixture.
    1. Hand picking
    2. threshing
    3. winnowing 
    4. sieving 
  • separation of insoluble solids from solid – liquid mixture.
    1. sedimentation and decantation
    2. filtration
  • separation of soluble solids from a mixture
    1. Evaporation
  • separation of liquid from a mixture
    1. condensation
    2. distillation

2. How can you separate a mixture of clay and water?

Ans :-  separation of mixture of clay and water will be done by the method of sedimentation and decantation because clay is insoluble in water and heavier than water so clay  will settle down at the bottom of vessel and then clear water will be separate out by the process of decantation .

B. Science Riddles :-

1. I am an important component of your food and found in every kitchen. i am extracted from water , but not from fresh water . which process is used to extract me?

Ans :-  that important component of our food is “salt” which is extracted from the seawater by the process of evaporation.

2. I am a liquid transparent like water . i am not soluble in water. how would you separate me when i am in water.

Ans :-  oil is insoluble in water and it can be separate out by the process of decantation.

C. Multiple choice questions :-

Tick (\surd) the correct options.

1. Meena prepare soup for her grandmother . there are pieces of vegetables in the soup . grandmother does not want to have vegetables pieces in the soup . Meena removes the vegetables pieces from the soup by 

  • (a) evaporation and condensation 
  • (b) sedimentation and decantation
  • (c)filtration    \surd
  • (d)hand picking

Ans :-  (c) filtration

2. Sameer has a sample of raw rice in a container . He adds water in the container to wash it . After some times , the dust particles comes to the surface while the rice grains settle down at the bottom. which one of the following process helped Sameer to remove the dust particles.

  • (a) Filtration and evaporation 
  • (b) condensation and evaporation. 
  • (c)evaporation and sedimentation
  • (d) sedimentation and decantation    \surd 

Ans :-  (d) sedimentation and decantation

3. A salt solution gets saturated when a student mixes 5 g of salt in 30 ml of water in a beaker . The student further add 5 g of salt in the solution . He observes that the salt does not dissolve in the water. He then adds 20 ml of water in the beaker and observes that the some of the salt has dissolved . How much more water is needed to dissolves in the remaining salt.   

  • (a) 5 ml
  • (b) 10 ml   \surd 
  • (c) 2 ml
  • (d) 8 ml  

Ans :-  (b) 10 ml

Section - B

A. very short answer questions :-

1.  Identify the solute and solvent in saline , which is injected in you when you suffer from dehydration.

Ans :-  solute :- sodium chloride and solvent :- water

2.  in what kind of mixture sieving is used ?

Ans :-   the method of separating the component of mixture that are of different sizes by using a sieve called sieving . ex:- separating stones from sand.  

3.  why is threshing an important step in the process of harvesting crops ?

Ans :-   because threshing is used for the separation of large quantities of grains.

4.  in which two separation step methods vapours are end forms. ?

Ans :-   evaporation and condensation. 

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